GB2273307A

GB2273307A - Drive station for mining machines and conveyors

Info

Publication number: GB2273307A
Application number: GB9325481A
Authority: GB
Inventors: Gerhard Briehl
Original assignee: Dorstener Maschinenfabrik AG
Current assignee: Dorstener Maschinenfabrik AG
Priority date: 1992-12-12
Filing date: 1993-12-13
Publication date: 1994-06-15
Anticipated expiration: 2013-12-13
Also published as: PL301412A1; PL172655B1; GB2273307B; CN1089330A; AU5230593A; CN1035893C; AU663423B2; RU2094349C1; GB9325481D0; US5402879A

Abstract

A drive station for winning machines and scrape chain conveyors used in mining operations comprises a main drive and an auxiliary drive, each drive having a measuring and control unit 7 for a drive motor 1 and safety slipping clutch 6. During heavy start and heavy run respectively, a control sensory means detects the undershooting of a limit speed of the drive motors, which is preselectable according to a program, and a drive control shifts simultaneously or successively into a slow speed step. After overshooting a preselectable limit speed of the slow speed step, the drive control shifts into the fast speed step. Moreover, the drive force of the safety slipping clutches can be adjusted during the starting process. <IMAGE>

Description

1 2273307 1

Description

The invention relates to a drive station for winning machines and scraper chain conveyors used in mining operations, comprising a main drive and an auxiliary drive, each equipped with drive motor, gear and controllable safety slipping clutch, and a measuring and control unit for controlling the drive motors and safety slipping clutches.

Problems with start and in particular with the so-called heavy start of scraper chain conveyors and winning machines are solved only unsatisfactorily when using presently common pole-changing drive motors and diesel engines with steep characteristic curves inherent to such aggregates.

Although a drive system for the socalled heavy start and heavy run respectively is already available for the use of pole-changing drive motors having an increased torque sequence in low speed steps, the protective operating method also required, particularly the prevention of loose chains or sagging chains and shock loads on chains and driving parts of winning machines, scraper chain conveyors and the like, is left out of consideration. The use of a power shift gear reinforces the occurring shock loads, i.e. the torques transmitted to driving parts and chain by the motor in the low step of the power shift gear increase substantially. In fact efforts have been made to protect heavy start or heavy run by using variable hydrodynamic couplings but the large space required for ducts of operating fluid and cooling of which is a disadvantage. Moreover, the secondary wheel and its relatively large centrifugal arranged on the fast running gear shaft of the secondary transmission exhibit unfavourable effects at least on 2 sudden braking, e. g. on sudden blocking or errating load increases. In addition, a continuous and essential power loss must be accepted due to unavoidable permanent slipping.

The invention is based on the object to provide a drive station for winning machines and scraper chain conveyors used in mining operations in the initially described embodiment, which is characterized by a driving system designed for functional performance of heavy start and heavy run respectively, and which avoids loose chains such as planing chains or conveyor chains as well as sagging chains.

Relating to a drive station in this class, the invention accomplishes this object in that a control sensory means detects undershooting of a limit speed of the drive motors, which is preselectable according to a program, whereby a drive control simultaneously or due to the detection shifts main drive and auxiliary drive and vice versa, respectively, into a slow speed step, and in that shifting again into the fast speed step is effected after a limit speed of the slow speed step preselectable according to a program has been exceeded. Within the scope of the invention, for initiating the shifting into the slow speed step, the control sensory means can detect the thermal load of the drive motors from the temporal course of the speed drop and compare it with the cooling available for the drive motors in order to prevent inadmissible heating and early disconnecting of the drive motors. The invention teaches in addition that the safety slipping clutch of one of the two drives (main drive or auxiliary drive) - or the safety 3 slipping clutches of both drives (main drive or auxiliary drive) - can be set in slipping motion simultaneously or successively and closed again after acceleration of the drive motor(s) on reaching a low limit speed preselectable according to a program, or on moving into smooth blocking after undershooting of a low limit speed preselectable according to a program in the fast and slow speed step. "Smooth Blocking" within the scope of the invention means steady load increase in contrast to hard blocking which is supposed to mean erratic load increase.

In drive systems having safety slipping clutches in the range of steep characteristic curves of drive motors typically used in mining operations, normally asynchronous motors, a load compensation control is effectuated on the currently higher loaded drive motor by defined, short-time slipping after power comparisons and comparison of current consumption, respectively, with overloading a scraper chain conveyor with for instance coal, rubbish and the like.

Then, if the load on the drive motors increases more, a "Heavy Run" occurs or the scraper chain conveyor moves into a so-called "Smooth Blocking". on undershooting a limit speed, which is preselectable according to a program, is detected by the control sensory means of the drive station, the drive control automatically shifts main and/or auxiliary drive simultaneously or successively into the slow speed step. The limit speed may typically be before, but also behind the breakdown torque as highest torque of the drive motors. After a "Relieving Motion" of the scraper chain conveyor in the slow speed step, automatic shifting into the fast speed step occurs after an upper limit speed of the slow speed step has been reached, whereby the upper 4 limit speed of the slow speed step is selected according to a program, taking into account the torque sequence in the fast speed step. Provided however, that the steep decreases further, the drive station moves into smooth blocking, and the safety slipping clutch of one of both drives or both drives (main and auxiliary drive) are simultaneously or successively moved into slipping by controlled clutch thrust, and then closed again after previous load compensation control for full utilization of the dr. ive motors on reaching the lower limit speed of the fast or slow speed step preselectable according to a program in drive stations with safety slipping clutches according to the invention. Hereby the rotatory energy of the drive motor to overcome blocking is optimally used in addition to the breakdown moment. Moreover, incalculable shock loads and impact loads respectively on the chain, e.g. by sudden tension of the chain band, do not occur. The drive station will be disconnected if a steady operation cannot be achieved inspite of programmed pressure force increase of the concerned safety slipping clutch, and the control process can be repeated if required. The blocking cause must be eliminated before a new start. With errating load increases, e.g. on moving into a hard blocking, the safety slipping clutch of the uncontrolled drive (main drive or auxiliary drive) func- tions as overload protection for chain and drive station. According to a preferred embodiment of the invention with independent significance, the pressure force of safety slipping clutches during starting or heavy running or on smooth blocking is independently adjustable, continuously or in progressive steps.

In order to prevent inadmissible heating and thus disconnection of the drive motors, the drive control detects in addition to the limit speed also the thermal load on the drive motors before initiating the shifting into the slow speed step in heavy runs or moves into smooth blocking. The thermal load is determined either directly or from the temporal course of the speed drop detected by the control sensory means and evaluated in the drive control. The thermal load is compared with the currently available cooling. If in heavy running operations required, the coolant flow rate can be increased automatically and temporarily by means of the drive control.

Moreover, hardwired temperature measuring heads may be 15 inserted directly between the disks of the fixed disk carrier of safety slipping clutches designed as multi-disk clutches in the drive aggregate according to the invention. In addition, the wear condition of multi-disk clutches and safety slipping clutches respectively can precisely be detected by means of hardwired proximity switches designed as transducers via changed piston positions of the closed multi-disk clutches and safety slipping clutches respectively. The measured values can then be transmitted to the measuring and control unit for evaluation. Such measures are recommended if temperature course and wear condition of safety slipping clutches and their clutch disks must be accurately determined, for instance on engaging safety slipping clutches during the starting process and, in the case of multiple drives, on engaging safety slipping clutches or multi-disk clutches in temporal sequence.

6 The invention will now be explained in more detail with reference to a drawing presenting an embodiment by way of example only, in which:

Figure 1 is schematic side view a scraper chain conveyor with drive stations according to the invention, and an intimated sagging chain, Figure 2 is a schematic representation of a starting process to prevent the chain from sagging or getting loose in the through of a scraping chain conveyor.

Figure 3 is a sectional view of a tightened chain in a chain guiding mechanism, Figure 4 is a sectional view of a loose chain in a chain guiding mechanism, and Figure 5 shows schematically a drive station according to the invention.

Referring to Figures 1 and 2, a starting process to prevent a chain from sagging or getting loose in the trough of a scraper chain conveyor with low prestress or heavy start will now be described by way of example only:

1. Normal Start.

h Acceleration of drive motor 1 for main drive without load.

7 1.2. Acceleration of drive motor 2 for auxiliary drive with reduced clutch thrust, is chain trough 3 is tightened, clutch of auxiliary drive slips.

1.3. The slip pulses of the auxiliary drive initiate the pressure force increase for the safety slipping clutches on main and auxiliary drive via the drive control.

1.4. The pressure force of the safety slipping clutches, e.g. multi-disk clutches, is increased according to a program until no more slip pulses occur.

1.5. The drive control shifts from "Starting" mode into normal operating mode.

The drive control disconnects the drive motors 1, 2 again and switches to "Heavy Start" mode, if the programmed pressure force increase does not achieve to stop the safety slipping clutches, i.e. slip pulses continue to occur.

2. Heavy Start.

2.1. Steps 1 to 1.3 as in normal start.

2.2. According to the "Heavy StarC program the pressure force of the safety slipping clutches is momentarily 30 increased to values which allow to transmit the motor breakdown moment to main and auxiliary drive. With further increase the starting process can be sup 8 ported additionally by the rotatory energy of drive motors 1, 2.

Regardless of the above example the pressure force of the safety slipping clutches is controlled after free acceleration of drive motors 1, 2 on main and auxiliary drives in such a way that the torque of the driving chain starwheels, and thus the starting acceleration of the concerned chain and conveyor chain respectively can be a:dapted to the respective operating condition of the scraper chain conveyor a) according to the type of load, and b) according to the starting resistance (e.g. after extended standstill) to be expected.

Regarding the pole-changing drive motors 1, 2 this may take place in the high as well as in the low speed step. Various starting programs in the control device are available for this purpose. Provided that the preselected starting program does not bring about a start, the effective data of the starting attempt such as f slip course of the safety slipping clutches (e.g. pulse sequence), power characteristic and power consumption respectively of the drive motors 1, 2 of main and auxiliary drive 9 are automatically converted into a program proposal (e.g. heavy start) in an evaluation unit of the control unit.

With specified prestress of the conveyor chain, a controlled starting process prevents the occurrence of socalled loose chains and sagging chains respectively. Hereby, a controlled pressure build-up in the safety slipping clutches, e.g. corresponding to the temporal slip pulses of the respective safety slipping clutch and the speed values sufficient for the drive speed respectively, which are evaluated in the measuring and control unit and detected by the control sensory means, and which may be different for main and auxiliary drive, accelerates the scrape chain conveyor in accordance with the program until the safety slipping clutches do not slip any more, and the full speeds are transmitted to the starting shafts via the safety slipping clutches. From now on no additional efficiency loss due to slipping occurs.

Provided that the occurrence of a so-called loose chain and sagging chain respectively cannot be prevented, e.g. with insufficient prestress of the conveyor chain or overloaded scrape chain conveyor, a programmed tuning of the main and auxiliary starting processes, initiated by the drive control, deposits the loose or sagging chain section on the scrape chain conveyor in such a way that this loose or sagging chain section is harmless for the ongoing operation of the scrape chain conveyor and does not interfere with it.

Shock loads on conveyor chain and driving parts, e.g. by suddenly tightening the loose conveyor chain on starting the scrape chain conveyor/ are prevented af ter / load-free acceleration of drive motors 1, 2 by the controlled pressure build-up in the safety slipping clutches, even when using drive motors 1, 2 and asynchronous motors respec- tively having a steep characteristic curve, whereby the rotatory energy of drive motors 1, 2 for starting the scrape chain conveyor can be fully exploited, i.e. overdimensioning of drive motors 1, 2 and electric motors respectively to bring about the starting processes is not required. Therefore, operating costs are minimized.

Figure 5 shows a drive station according to the invention applicable to the main drive as well as for the auxiliary drive. This drive station for a winning machine and for a scrape chain conveyor 4 respectively comprises a drive motor 1 and a downstream gear 5 as well as a safety slipping clutch 6 admittable by a pressure means. The gear 5 may be a branching gear and a planetary gear respectively and, in the case of the safety slipping clutch 6, a multi- disk clutch. The safety slipping clutch 6 is in any case equipped with a slip monitor as transducer for a measuring and control unit 7 to actuate the safety slipping clutch 6. The safety slipping clutch 6 in the embodiment example is concentrically arranged within the transmission path and transmits a supporting moment of either the hollow wheel or of the planet carrier of the gear designed as planetary gear to the gearbox casing. The measured values supplied to the control unit are electronically evaluated. On overshooting the correspondingly allocated specified value, the measuring and control unit 7 actuates safety slipping clutch 6 and drive motor 1 by means of an electronic con- v 11 trol 8 and, to be precise, with an in-line arranged hydraulic and pneumatic control 9 respectively.

12

Claims

C 1 a i m s is 1. A Drive station for winning machines and scrape chain

conveyors (4) used in mining operations consisting of a 5 main drive and an auxiliary drive, each having a drive motor (1 and 2 respectively), a gear (5), a controllable safety slipping clutch (6), and a measuring and control unit (7) for main and auxiliary drive to control the drive motors (1 and 2 respectiVely) and the safety slipping clutch (6), characterized in t h a t a control sensory means detects undershooting of a limit speed of the drive motors (1, 2), which is preselectable according to a program, and a drive control shifts simultaneously or successively into a slow speed step, and in that after overshooting a limit speed of the slow speed step, which is preselectable according to a program, shifting again into the fast speed step is effectuated.
2. A drive station according to claim 1, characteri z e d i n t h a t the thermal load on the drive motors (1, 2) is detected by the control sensory means from the temporal course of the speed drop and compared with the cooling available for the drive motors (1, 2) in 25 order to prevent inadmissible heating and early disconnection of the drive motors (1, 2), when initiating the shifting into the slow speed step.
3. A drive station according to claim 1, characterized in that the safety slipping clutch (6) of one of both drives - or the safety slipping clutches (6) of both drives simultaneously or successively - are 13 caused to slip on reaching a lower limit speed in the fast or slow speed step, which is preselectable according to a program, and closed again after acceleration of one or both drive motors (1 or 2).
4 A drive station according to any of claims 1 to 3, characterized in t h a t with control of one drive the other drive with its safety slipping clutch takes over the overload protection for chain and drive station.
5. JA drive station for winning machines and scrape chain conveyors used in mining operations, with main drive and auxiliary drive, each having a drive motor (1 and 2 respectively), a gear (5) and a controllable safety slipping clutch (6), and a measuring and control unit (7) for main and auxiliary drive to control the drive motors (1, 2) and the safety slipping clutches (6), characterized in t h a t the pressure force of the safety slipping clutches (6) is separately adjustable continuously or in progressive steps during the starting process or heavy run or on smooth blocking.
6. A drive station according to claim 5, characteri z e d i n t h a t the controls of drive motors (1, 2) and safety slipping clutches (6) communicate with each other during the starting process.
7. A drive station according to claim 5 or 6, c h a r a c - t e r i z e d i n t h a t the starting processes, varying 14 under operating conditions, are preselectable according to a program.
8. A drive station according to claims 5 to 7, c h a r a c t e r i z e d i n t h a t measured data detected during a starting process are supplied to an evaluation unit, and programmed repeated starts are automatically initiated in dependence on the evaluation results.